Torque Sensor With Segmented Measuring Pockets
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Solution Overview
Problem
Existing torque sensors face challenges in achieving high measurement accuracy and sensitivity due to disruptive bending stresses and parasitic forces, especially in short shaft sections with limited axial space, where traditional designs either suffer from measurement sensitivity reduction or excessive length, interfering with the strain gauge body.
Innovation Solution
A compact torque sensor design featuring coaxially peripherally closed measuring pockets and stiffening webs, with membrane-like expansion zones and radially arranged shear force transducers, which minimizes disruptive forces and enhances torsional rigidity, allowing for high measurement accuracy and sensitivity while maintaining a low mass moment of inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the torque sensor is designed to be very short in the longitudinal direction with two rotationally symmetrical fastening flanges, then the axial space requirement is reduced, but the measurement accuracy deteriorates due to disruptive bending stresses and parasitic forces
Solution Approach 1:
The torque sensor is segmented into distinct functional zones: fastening flanges for mounting, a torque transmission element for force transfer, and a measuring body with measuring pockets for accurate measurement. This segmentation isolates the measuring pockets from disruptive bending stresses generated at the fastening flanges, allowing short axial length while maintaining measurement accuracy.
Solution Approach 2:
The measuring pockets are extracted as separate deformation bodies from the solid torque transmission element. This extraction creates localized membrane-like expansion zones that are sensitive to torque but isolated from parasitic forces, enabling accurate measurement in a compact design.
2Force
If the measuring body is designed with large axial thickness to transmit entire torque, then the torque transmission capability is improved, but the measurement sensitivity is reduced
Solution Approach 1:
The measuring pockets are designed with localized thin-walled membrane structures that have high measurement sensitivity, while the overall torque transmission element maintains sufficient thickness for adequate torque transmission. This local quality differentiation allows the measuring zones to be sensitive without requiring the entire body to be thin.
Solution Approach 2:
The torque sensor employs a composite structure combining solid torque transmission regions with thin-walled membrane measuring pockets. This composite design allows different parts to serve different functions: the solid portions transmit torque effectively while the thin-walled pockets provide sensitive measurement capability.
3Length of moving object
If the fastening bores are arranged close to the measuring webs for compact design, then the axial space is reduced, but the measurement accuracy deteriorates due to disruptive bending stresses
Solution Approach 1:
The measuring pockets are extracted as separate deformation bodies positioned at an optimal distance from the fastening bores. This extraction allows the fastening structure to be compact while the measuring pockets remain isolated from disruptive bending stresses, maintaining measurement accuracy.
Solution Approach 2:
The torque transmission element acts as an intermediary between the fastening flanges and the measuring pockets. It transfers torque from the fastening regions to the measuring pockets while isolating the sensitive measuring zones from parasitic forces generated at the fastening interfaces.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves high measurement accuracy and sensitivity with reduced parasitic forces, enabling high-speed torque measurement up to 50,000 revolutions per minute and accommodating various torque ranges, while maintaining a compact and lightweight structure.
Implementation Method 1
strain gauges are applied, which deliver an accurate measurement signal that is proportional to the transmitted torque
Implementation Method 2
The measuring pockets create thin, membrane-like expansion areas as deformation bodies
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a torque sensor which consists of two disc-shaped fastening flanges (1, 2) which are opposite and parallel to one another and are connected to one another by means of a radially inner torque transmission element (3). In this case, one fastening flange (2) is designed as a measuring flange which has, between the outer fastening annular surface (10) thereof and the torque transmission element (3), in a coaxially circumferential region, a plurality of recesses (5, 5'), to the outer surfaces (19) or bases (15) of which shear force sensors (20) are applied. The invention is characterized in that the recesses (5, 5') are formed by at least three measuring pockets which are separated from one another by means of at least three radial stiffening webs (6). In this case, the measuring flange (2), in the radially inner region thereof with respect to the radially outer fastening annular surface (10), is in the form of a circumferential closed surface to which the measurement electronics are fastened, which electronics are hermetically sealed with a cover.